Please provide the following details to expedite Pull Request review:
Checklist
- [x] ~Checked if it requires a pylibjuju change?~
- [ ] ~Added integration tests for the PR?~
- [ ] ~Added or updated doc.go related to packages changed?~
- [x] Do comments answer the question of why design decisions were made?
Description of change
By default, k8s keeps 10 latest replica sets records.
Juju prefers no history records should be kept, so this PR sets it to 0.
Drive by fix: validates ScalePolicy for non-stateful charms;
QA steps
deploy a stateless charm then run upgrade-charm after changed k8s specs;
console
# replicasets should always be one record per application;
$ mkubectl -n gitlab-k8s get rs -n t1
Documentation changes
No
Bug reference
https://bugs.launchpad.net/juju/+bug/1864394
该提问来源于开源项目：juju/juju
